<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			*{margin: 0;padding: 0;}
			#pa{
				width: 100%;
				height: 90rem;
				background-color: gray;
				position: relative;
			}
			.ch{
				width: 50%;
				height: 50rem;
				background-color: #00FFFF;
				position: absolute;
				top: 50%;
				left: 50%;
				transform: translate(-50%,-50%);
			}
		</style>
	</head>
	<body>
		<div id="pa">
			<div class="ch">
				
			</div>
		</div>
	</body>
</html>
